A wireless access scheme and a wireless network of cellular mobile communication (hereinafter, referred to as “long term evolution (LTE)” or “evolved universal terrestrial radio access (EUTRA)”) have been developed by the 3rd generation partnership project (3GPP). In LTE, an orthogonal frequency division multiplexing (OFDM) scheme is used as a communication scheme of a downlink. Further, in LTE, a single-carrier frequency division multiple access (SC-FDMA) scheme is used as a communication scheme of an uplink. In LTE, a base station device is referred to as an evolved NodeB (eNodeB), and a mobile station device is referred to as user equipment (UE). LTE is a cellular communication system in which a plurality of areas which are controlled by base station devices are arranged in a cell-like shape. A single base station device may control a plurality of cells.
LTE corresponds to Time Division Duplex (TDD). The LTE employing a TDD scheme is referred to as TD-LTE or LTE TDD. The TDD is a technology that allows full-duplex communication in a single frequency band, by performing time-division multiplexing of an uplink signal and a downlink signal.
In 3GPP, it has been considered to apply a traffic adaptation technology for changing the ratio of the number of uplink resource to the number of downlink resource depending on the uplink traffic and the downlink traffic. In NPL 1, a method of using a flexible subframe has been presented as a method of realizing such traffic adaptation. A base station device can receive an uplink signal or transmit a downlink signal in the flexible subframe. In NPL 1, the mobile station device regards the flexible subframe as a downlink subframe, unless the base station device indicates the transmission of the uplink signal for the flexible subframe.